1. Field of the Invention
The present invention relates to a semiconductor integrated circuit device and a control method therefor, and more particularly to a semiconductor integrated circuit device capable of reading information inherent to each chip at the time of testing or evaluation and a control method therefor.
2. Description of Related Art
Latest semiconductor devices store, within their nonvolatile devices, various items of product information specific to each chip (including the production plan, production lot number, wafer number and chip number) to ensure accurate tracking of faults in the market, and those items of information are made readable from outside in a packaged state.
As an example of the prior art, a technique disclosed in Japanese Unexamined Patent Publication No. 2000-315772 will be described with reference to FIG. 10. Pulse signals inputted to a clock pad Pc are counted by a binary counter 24 via a buffer circuit IBc, and binary data resulting from the counting of the pulse signals are supplied from this binary counter 24. A comparative decision circuit 22 compares binary data, which are the output of the binary counter 24, and data stored in a data holding unit 21 and, when the two sets of data are found identical, that decision result of identity is outputted to a pad P0 via a decision result output circuit 23. The outputting method is to output the result of decision by the comparative decision circuit 22 (identity) by causing a current to flow to the pad P0.
The binary counter 24 is configured by connecting in series a plurality of unit circuits (not shown). And there are provided as many unit circuits as corresponding to the number of bits of data specific to the chip stored in the data holding unit 21. For instance, where each of the items of information including the lot number, wafer number and chip number are to be stored as 10-bit specific data, the binary counter 24 is configured by connecting 10 unit circuits in series.
A pad in this context is an external terminal by which the semiconductor integrated circuit device and the outside are interfaced.